(1) Field of the Invention
The present invention pertains to an improved locking pin mechanism for use with a locking dog of the type commonly used to install earth anchors.
(2) Background of the Invention
Utility poles and other tall narrow structures are generally secured by both being placed deep into the earth that supports them and then anchoring them through the use of extending guy wires. The guy wires provide for support to prevent the structure from levering itself from its hole in the earth. The guy wires will generally extend from an upper portion of the pole or structure and will be connected to a device which will hold their opposing end to the earth at a distance from the base of the pole or structure. The device is generally referred to as an “anchor” and the anchor and guy wire arrangement prevents movement of the upper portion of the structure which could act to lever the structure through the ground tipping it over.
A myriad of anchor assemblies are available for use in different types of soils and substances and for different types of applications. One particularly common type of anchor used in the support of utility poles and other pole-like or tower structures is the screw type anchor (10) such as that shown in FIG. 1 and in U.S. Pat. No. 3,148,510 the entire disclosure of which is herein incorporated by reference. The screw type anchor (10) incorporates at least one screw flange (11) generally arranged toward the lower end (13) of the anchor (10) and a guy rod (15) which extends upwards from the screw flange (11) and is screwed or otherwise attached thereto. The guy rod (15) will generally terminate at its upper end (14) in a connector (17). The connector (17) will often be an externally threaded shaft (19) with a shoulder (21). While anchors (10) are particularly useful for the installation of guy wires, they are also used for the direct installation of tall structures (particularly those which are narrow and lack other foundations) such as street lights, transformers, bumper posts, and signs.
Anchors of this type are regularly installed in conjunction with the erection of a utility pole. An auger truck carries and controls the auger for drilling the pole's hole and includes a derrick structure for transferring rotary motion from a motor on board the auger truck to whatever object is attached to the derrick. The attachment will generally be at the terminal end of the derrick and will generally be a Kelly bar. The Kelly bar may be comprised of multiple segments connected together. When an auger is in use on the derrick, generally one of the segments of Kelly bar will extend through the central shaft of the auger and the auger will be attached toward the derrick and toward the top of the Kelly bar. If additional length is needed for the auger from the derrick (for instance in deep installations or when the truck is positioned on a hill or other inclined area), the auger may be positioned so that it is attached at the terminal end of the Kelly bar, instead of having the Kelly bar extend through the shaft of the auger, to provide for additional length to the auger from the derrick.
To install an earth anchor, generally the first step is to remove the auger from the derrick. Once the auger has been removed, a combination of devices for attaching the Kelly bar to the anchor (10) would be used. One such set of devices of the prior art is shown in FIG. 2. The design and operation of such devices is discussed at length in U.S. Pat. No. 3,377,077, the entire disclosure of which is herein incorporated by reference, but a general overview will be given here. The device comprises a connector (50) for connecting the Kelly bar to the locking dog (200) which in turn connects to a drive wrench (60). The locking dog (200) includes a sleeve (207) attached to a bolt flange (205). The sleeve (207) includes a non-circular, generally polygonal bore (209) thereinto. The non-circular cross-section of the bore (209) is utilized to prevent the drive wrench (60), when placed into the bore (209) in a socketing type of arrangement, from rotating relative to the bore (209). By convention, the bore (209) is usually square in cross-section.
The drive wrench (60) is generally fixed in position through a combination of cross-sectional shape and the inclusion of a pin locking mechanism in the locking dog (200). The drive wrench (60) includes two holes (61) through its outer surface and located towards its upper end (63). The locking dog (100) includes a pair of laterally extending sleeves (211) and (213), each of which includes a spring biased pin (221) and (223) located within each lateral sleeve (211) and (213), and normally biased inwardly so that one end of each pin extends into the bore (209). Rings (231) and (233) or other grasping aids may be provided upon pins (221) and (223) to facilitate a worker in pulling them outwardly, against the biasing. There may also be support mechanisms provided to hold the pins (221) and (223) in an outward position in the form of a stepped arrangement.
Each of the two pins (221) and (223) extends into the bore (209) of the locking dog (200) a predetermined distance at a first position to which it is naturally biased. Further, each of the pins (221) and (223) may be retracted and held in two different positions by pulling on the ring (231) or (233) and rotating the pin (221) or (223) to engage steps on the ends of the sleeves (211) and (213). In a second position, the pin (221) or (223) is partially retracted from the bore (209), and in a third position the pin (221) or (223) is fully retracted from the bore (209) as seen in FIG. 3. Each pin (221) and (223) will generally also include a slanted face (225) which extends from the innermost end of the pin (221) or (223) to a point along the pin's (221) or (223) length prior to the other end. When in the first position, this point along the pin's (221) or (223) length is within the bore (209) providing for a small ring (291) of the pin (221) or (223) to interact with the drive wrench (60).
To mount the anchor (10) to the derrick in preparation for installation, the drive wrench (60) is first placed into the bore (209) of the locking dog (200) with the pins (221) and (223) at their third (most retracted or outermost) position (FIG. 3C). While holding the drive wrench (60) in place in the bore (209), a worker will reach to the upper end (63) of the drive wrench (60) and rotate the pins (221) and (223) which releases them to their first position (FIG. 3A) which allows them to pass into the bore (209) and through the holes (61) in the drive wrench (60). With the drive wrench (60) so secured to the locking dog (200), the guy rod (15) is then threaded into the lower end (65) of the drive wrench (60). As the guy rod (15) is threaded through the drive wrench (60), the upper end (14) of the guy rod (15) will contact the slanted faces (225) of the pins (221) and (223) forcing them to move from the first position toward their second (FIG. 3B) (or even third) position although they will generally retract linearly instead of being rotated. The shoulder (21) will do the same when it contacts the slanted faces (225). It should be apparent that so long as the guy rod (15) fits inside the drive wrench (60), this movement will not allow the locking dog (200) to release the drive wrench (60) as the pins (221) and (223) will always be at least partially within the holes (61) in the drive wrench (60). Once the shoulder (21) passes over the pins (221) and (223), the pins (221) and (223) will be biased back under the shoulder (21) allowing the anchor (10) to be supported by the pins (221) and (223) and therefore attached to the locking dog (200).
At the time this attachment occurs, drive wrench (60) will have preferably mated with a device of similar shape to the drive wrench (60) above the screw flange (11) on the anchor (10). This mating will generally result in one of the two pieces socketing into the other. As the drive wrench (60) and this device preferably also have non-circular cross-sections, this socketing connection prevents the anchor (10) from rotating relative to the drive wrench (60) allowing the rotational motion imparted on the drive wrench (60) by the rotation of the locking dog (200) to be transferred to the anchor (10).
The anchor is then installed by activating the rotary movement of the auger truck's motor and boring the anchor into the ground using a screwing or drilling type action. Once the screw flange (11) is at the desired depth, the rotary motion provided by the auger truck will be stopped. The pins (221) and (223) will then be retracted and secured in their second position (FIG. 3B) which will free the guy rod (15) but not the drive wrench (60) and the auger truck will lift the derrick pulling the drive wrench (60) free of the guy rod (15). Once free, the guy rod (15) will generally be capped with an eyelet to cover the externally threaded shaft (19), and the anchor (10) is ready to be used. To lay another anchor (10), the pins (221) and (223) are returned to their first position (FIG. 3A) and the next anchor's (10) guy rod (15) is threaded through the drive wrench (60) as discussed above and the process is repeated.
While this process for laying anchors (10) has been used for many years, there are significant steps which are both cumbersome and dangerous in its performance. In particular, seating the drive wrench (60) in the locking dog (200) bore (209) is unnecessarily cumbersome as the worker has to reach up and manually release the pins (221) and (223) from their third position (FIG. 3C) to their first (FIG. 3A) while holding the drive wrench (60) in place. As the drive wrench (60) is generally about 4 feet or more in length, this can be very difficult. Further, the stepped locking mechanism for the pins (221) and (223) to support them in their second (FIG. 3B) and third (FIG. 3C) positions can allow for the grasping rings (231) and (233) to slip unexpectedly when trying to install or remove the guy rod (15) or the drive wrench (60).